Lead coating process



United States Patent O LEAD COATING PROCESS Fred E. Kendall, ChagrinFalls, and Paul Golar, South Euclid, Ohio, assignors to Steel Ceilings,Inc., Cleveland, Ohio, a corporation of Ohio No Drawing. ApplicationJune 13, 1952,

Serial No. 293,419

7 Claims. (Cl. 117-130) This invention relates as indicated to leadcoatings, and more particularly to protective coatings for metalsurfaces subject to corrosion, especially iron, steel and ferrousalloys.

The tendency of the less noble metals to revert to their naturallyoccurring states has been recognized since their first employment, andmany different methods have been adopted in an attempt to prevent,arrest or inhibit such corrosion or rusting. It has been estimated thatthe annual monetary loss due to corrosion in the United States alone isin excess of $5,500,000,000. Of course, indirect losses due to escape ofsuch materials as oil, water, natural gas and other fluids from corrodedpipe lines and losses due to down time in transportation facilities andmanufacturing plants are difiicult to appraise accurately. It shouldalso be appreciated that construction members and processing equipment,for example, are regularly overdesigned to compensate in part foranticipated corrosion. Very large industries have developed providingmethods and materials for protecting metal surfaces, including paints,varnishes, lacquers, phosphate coatings, tin plating, galvanizing, andother plating procedures such as the electroplating of zinc, cadmium,copper and nickel. Cathodic protection of pipe lines and the like hasrecently been developed on a large scale. Obviously, in view of thetremendous quantity of ferrous metals in use, any method of protectingthe same even slightly more effectively than methods currently employedwould result in a comparable extremely large annual dollar saving.

Each of the known methods of protecting ferrous metal surfaces hascertain inherent deficiencies and each such method will ordinarily beemployed only in certain selected fields of use. Protective organiccoatings, which include the paints and lacquers, are reasonablyeffective as long as the protective film is not broken, but they tend tobe rather expensive and often their cost is justified on the basis oftheir decorative qualities equally with their protective qualities. Theapplication of metallic coatings both by hot dipping and electroplatingis also an old art. The less noble metals such as zinc are generallyanoidic with respect to iron in most environments and are classified assacrificial. The protective coating gradually corrodes away and affordsconsiderable protection as long as a continuous film remains. There aresituations, however, where zine as well as lead, tin, cadmium andaluminum will reverse its potential with respect to iron andconsequently the position in the electromotive series cannot be whollyrelied upon as an infallible index for predicting the galvanic behaviorof metallic couples in all environments. Coatings of non-sacrificialmetals such as nickel and copper may also form galvanic cells with ironalthough the current flow is in the opposite direction to that in thecase of the sacrificial metals, resulting in accelerated corrosion ofthe base metal wherever the coating is broken or porous. Relativelythick coatings of such non-sacrificial metals are accordingly commonlyemployed.

Hot dip methods of applying protective metal coatings have certainadvantages over similar coatings electrodeposited but also displaycertain inherent weaknesses. Thus, hot dip galvanized steel may developcracks when flexed due to the formation of a hard zinc-iron alloy whichis brittle and has poor adhesive properties. The hot dip method and theelectroplating method both tend to produce coatings rather non-uniformin thickness.

It is accordingly a principal object of the present invention to providea protective lead coating for metal surfaces silllbject to corrosion,particularly iron, steel and the ferrous a oys.

Another object is to provide such coating which will be considerablyless expensive than other coatings commonly employed for a like purpose.

A further object is to provide such coating and method of application ofthe same which will be adapted to substantially all sizes and shapes ofarticles to be protected and will afford a predictable uniform degree ofprotection.

Still another object is to provide such coating which will not interferewith subsequent working of the article or the application of otherdecorative coatings and the like but instead will facilitate the same.

Other objects of this invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said inventionthen comprises the features hereinafter fully described and particularlypointed out in the claims, the following description setting forth indetail certain illustrative embodiments of the invention, these beingindicative, however, of but a few of the various ways in which theprinciple of the invention may be employed.

Briefly stated, our invention comprises the provision of a continuouslead coating on the metal surface to be protected by chemicaldisplacement from a bath containing the lead ion in solution. Moreparticularly, we have found that a remarkably effective lead coating maybe deposited on ferrous surfaces from a bath having a pH less than 7 andcontaining one or more aliphatic monobasic hydroxy acids.

The aliphatic mono-basic hydroxy acids such as glycolic, lactic andgluconic acid form soluble lead salts which do not require the presenceof ammonium or alkali metal salts as solubilizers. Since these leadsalts are highly soluble, it is possible to obtain a high lead ionconcentration, and the hydrolysis of iron is repressed as the result ofthe presence of the hydroxy groups. Other examples of such acids areglyceric and erythronic which, however, are relatively expensive.

Lactic acid may be selected as a particularly suitable aliphaticmono-basic hydroxy acid for our purpose inasmuch as it is relativelyinexpensive and commercially available in large quantities. It was foundthat a water bath containing lead lactate should be maintained at a pHof from about 2.5 to about 5.0 and preferably 3.4 to 4.2 and the leadion concentration should be maintained in the range of from about 50 toabout 250 grams per liter. Where the lead ion concentration isconsiderably below that indicated, the lead coating deposited on aferrous article immersed in the bath will be found to be relativelycoarse in crystalline structure, poorly adherent to the base metal andlacking in malleability and ductility. More satisfactory deposits wereobtained utilizing lead ion concentrations of from about to 250 gramsper liter but 'when. concentrations exceeding 300 grams per liter wereemployed the resultant coatings were found to have poor adhesion to thebase metal, and the rate of deposition was appreciably reduced and thesurface was non-uniformly coated. In general, it was found that forconsistently satisfactory results under normal operating conditions itis desirable to maintain a lead ion concentration of from about 90 toaboutx grams per liter.

Utilizing a water solution of lead lactate having a lead ionconcentration of 120 grams per liter, it was found that a lead coatingof maximum thickness could be deposited at a temperature .ofaproximately 170 F. and a pH of 4.2. As a general working range,however, for commercial operation a pH of 3.8+ or 0.2 may readily bemaintained and affords excellent results.

It has also been found that whereas an increased operating temperaturetends to accelerate the deposition of the lead from solution theultimate thickness of the coating obtainable will be somewhat less thanwhen the deposition takes place at a lower operating temperature. Sincethe rate of deposition is reasonably rapid at 170 F. and a considerablythicker coating is ultimately obtainable than when the bath is operatedat a tempera ture of, for example, 200 F., it is contemplated that thenormal operating temperature will range between approximately 170-190"F., as indicated, in the case of the lead lactate bath. A satisfactorydeposit may be obtained from a solution at boiling point but it will notbe as thick as when a lower temperature is employed and such operatingconditions are obviously relatively impractical. Temperatures in theupper end of this range will ordinarily be employed only when speed isof the essence and a temperature below 155 P. will seldom be employedwhere a reasonable rapid rate of production is desired. Nevertheless, ifthe article to be coated may be left in the bath for an extended period(c. g. overnight) then a reasonably satisfactory coating may be achievedat room temperature (70 F.) or even somewhat lower.

It has, of course, been generally known prior to this invention thatlead as well as other metals could be plated out of solution by chemicaldisplacement but commercially acceptable coatings have not previouslybeen obtained by this process. In the past such coatings have beenextremely thin, coarse of texture, poorly adherent, and full ofpin-holes, rendering any protection afforded very slight.

Addition agents While an excellent lead protective coating can beobtained by carefully following the teachings of this invention withoutthe employment of special addition agents, much less care need beexercised when addition agents of the type commonly added toelectroplating baths for the purpose of ensuring sound metallic depositsare employed. Typical addition agents include: Carbohydrates such as thesimple sugars, dextrose, maltose, sucrose and lactose; and the morecomplex carbohydrates such as dextrin and the starches were found tofunction satisfactorily. Both animal and vegetable proteins such ascasein, bone glue, albumin, gelatin and zein served equally well. Someorganic acids such as tannic, pyrogallic, salicylic and gallic alsoproduced the desired efiect as addition agents. Special classes ofchemical compounds such as aldehydes, furfurals, phenols, cresols,aloin, goulac, licorice, resorcinols, naphthols, gums and amines servedas satisfactory addition agents. The concentration of addition agent inall cases was very small, usually in the range of 0.1 to 1 gram perliter of solution. Greater or less amounts could be used, but in mostcases, the concentrations indicated were preferred for commercialoperation.

Since some impurities such as traces of certain sugars commonly found incommercial grades of acids contemplated herein such as lactic acid maythemselves serve the purpose of addition agents, such less expensivegrades may be preferred to chemically pure acids although a supplementaladdition agent will also ordinarily be added. Of course, contaminantswhich would interfere with the displacement reaction or deleteriouslyaffect the coating will be avoided. The precise manner in which suchaddition agents operate to achieve the improved results has never beenwholly understood in the electroplating art and is equally mysterioushere. Their presence, however, definitely permits the obtaining ofsatisfactory coatings throughout a wider range of operating conditions,serving to inhibit grain crystallization.

Iron build-up and control Of course, as the lead is deposited on theferrous surface a corresponding amount of iron will pass into solutionand in due course of time a substantial change in the composition of thesolution will result. A probably reaction mechanism can be written asfollows:

The theoretical weight of lead thus deposited may be computed bymultiplying the increase in weight of the article being plated by afactor of 1.37. By actual test it is found that the reaction yield isnearly a factor of 1.38 being obtained.

Plating of lead by chemical displacement from a solution prepared fromthe aliphatic mono-basic hydroxy acids continues satisfactorily despitea considerable buildup of ferrous ion concentration and this greatlyfacilitates control of commercial operations. Thus, for example, at atemperature of 185 saturation will occur at a concentration of about 25to 30 grams per liter of ferrous ion, the ferrous lactate beginning tocrystallize and precipitate. However, 100 grams per liter orapproximately one pound per gallon of lead can be deposited beforeferrous ion saturation occurs. While satisfactory lead deposits areobtained from solutions saturated with ferrous ion, neverthelesssubsequent rinsing operations are somewhat facilitated ifcrystallization of ferrous lactate during operation is avoided. Ferrouslactate is readily soluble in cold Water and is therefore not a seriousproblem even when crystallization does occur. Its removal from theplating bath may be conveniently achieved by cooling the bath, whereupona large proportion will precipitate and may be removed by decanting or,preferably, by filtration.

Commercial operating conditions In preparing the bath or solution, alead acid concentrate of any of the water soluble aliphatic mono-basichydroxy acids may be used. After the concentrate has been prepared, itmay be diluted to any lead ion concentration desired between 50 and 400grams per liter of lead ion but the preferred concentration willordinarily be about grams per liter. By way of illustration, aconcentrate having 500 grams per liter of lead ion may be prepared asfollows:

A slurry of 585 grams PbO (litharge, 85% lead) in 375 ml. of water isprepared and while agitating slowly 526 ml. of lactic acid (85%) areadded, increasing agitation as the acid addition nears completion. Someheat may be required completely to solubilize the lead oxide or hastensuch solution. A clear solution of lead lactate is obtained having adensity of about 1.665 grams per ml. or 13.9 pounds per gallon. Thisconcentrate may be di luted as desired or added to an operating bath tomaintain the strength of the latter. A typical preferred solution mightcontain:

Components Gina/Liter Lbs/Gal.

Lead oxide (mono 140. 0 1. 17 Lactic acid (80%)..-. 168. 0 1. 40Addition agent.-. 0. 1-1. 0 Water to make up to Volume.

reclaim the lactic acid from the ferrous lactate produced could furthergreatly reduce this cost.

To control the lead ion, it is necessary only to analyze for iron insolution, and determine the specific gravity. The following chartillustrates the effect of accumulated iron on the solution at givenconcentrations of lead ion.

Although this method is not infallible, control can be exercised within5% which is adequate for commercial operation. If, for example, byanalysis, the iron was determined to be grams per liter and the specificgravity was determined to be 1.135, the column to the left indicates thepresence of 112 grams per liter of lead ion. If the initialconcentration was 120 grams per liter, the operator would know that 8grams per liter of lead had been deposited and needed to be replaced tomaintain the initial strength of the solution.

The solution may desirably be prepared initially in the form of aconcentrate having from 1000 to 200 grams per liter of lead ion, agreater concentration affording a too thick syrupy solution, difiicultto handle, and a lower concentration being relatively ineffectve toreplenish a depleted bath as well as containing an unnecessary amount ofwater if the solution is to be shipped. A range of from 800 to 500 gramsper liter is better for practical purposes and a concentration on theorder of 800 is preferred.

One of the interesting features of the novel coating solution of thisinvention is its versatility in mode of application. Satisfactorydeposits can be obtained by immersion, brushing on, flow coating, andspraying. The last-named method is often especially advantageous sincemuch of industry is geared to spray coat various types of materials forchemical surface treatment of metals as phosphating, chromating, and thelike. The mode of application will generally be dictated by thefacilities available and the size and shape of the articles to becoated. Insofar as we are informed, the deposition of a metal coating bychemical displacement from a spray application has never before beensuccessfully achieved.

As might be expected, the rate of deposition is greatest at the start ofthe operation and gradually lessens with time. The solutions may beprepared so that peak reaction equilibrium producing maximum thicknessof coating will occur in five, ten or fifteen minutes, for example.Sound deposits having a thickness of 0.0003 inch are easily obtainableand deposits having a thickness of 0.0005 to 0.00075 inch may beobtained when employing properly adjusted solutions. Coatings of suchthicknesses are much heavier than any obtainable by prior methods andare ample effectively to protect the underlying ferrous surface fromcorrosion.

It will, of course, be appreciated that before the work is coated itshould first be free of all oil, grease and dirt. Such prior cleaningoperation may, for example, include vapor degreasing or preferablytreatment with a chemical cleaner such as the commercially availablealkali, emulsion or two-phase cleaners. Following such cleaningoperation, the work should be thoroughly rinsed in water, and if free ofrust and scale it need not be acid pickled. If pickling should berequired, however, the work will again be thoroughly water rinsed aftercompletion of the pickling operation. It will then be conveyed to theprocessing tank or spray booth where metallic lead is deposited thereon'6 to the desired predetermined thickness. Subsequently, the work willbe rinsed first in cold water and then in hot water to facilitatedrying, forced warm air drying being preferred.

The lead coated article may receive supplemental surface treatments suchas chromating, oxalating, sulphating and phosphating in dilutesolutions. Under proper conditions, the lead may be bright-flowed whichfurther en'- hances its corrosion retarding ability. As a rule, however,these various supplemental treatments will be found unnecessary. Morefrequently, the finished coated article will merely be painted or oiled,the surface being particularly suited therefor.

Corrosion and weathering tests have shown ferrous articles coated inaccordance with the present invention to be exceptionally resistant tocorrosion. Ferrous articles lead coated in accordance with thisinvention will withstand approximately 48 to hours in the conventionalsalt spray test cabinet and, if oiled, considerably longer.

The employment of lead coatings to facilitate deep drawing operationsand the drawing of wire, and particularly the drawing of steel wire, hasbeen suggested since it has been determined that lead is a lubricant insuch drawing operations superior to the usual greases, oils, soaps,emulsions, etc., but such other methods have been generally adopted inthe industry for the reason that no economical method of applying thelead coating has previously been available. Thin lead coatings may alsoserve efficiently as a bearing metal in other applications.

Reclamation of aliphatic mono-basic hydroxy acids A process has beendescribed above whereby a lead coating may be deposited upon an iron,steel or ferrous article by chemical displacement from a solution of alead salt of an aliphatic mono-basic hydroxy acid. Lead lactate isdisclosed as a preferred example of a lead salt suitable for suchpurpose. As explained, however, the ferrous salt of the aliphaticmono-basic hydroxy acid which is formed by the reaction, graduallyaccumulates and will periodically be removed, additional lead salt beingadded from time to time to maintain proper operating concentration.Inasmuch as those aliphatic monobasic hydroxy acids which arecommercially available in any quantity, such as lactic acid, are quitevaluable, it is readily apparent that the cost of the chemicaldisplacement reaction may be much reduced if the acid can be reclaimedfrom the ferrous salt produced, and reused in the preparation ofadditional lead salt.

It is accordingly another object of this invention to provide a novelmethod of reclaiming aliphatic monobasic hydroxy acids from the ferroussalts thereof, and more particularly lactic acid from ferrous lactate.

A further object is to provide such method which will be relativelyinexpensive in operation and thus result ina considerable financialsaving in the cost of raw materials required for the maintenance of achemical displacement reaction for the deposition of a lead coatingonferrous articles from a solution of the lead salt of such aliphaticmono-basic hydroxy acid.

Still another object is to provide such method of reclaiming the acidwhich will also result in reclaiming the iron content in a form havingconsiderable commercial value.

As explained above, a very superior protective lead coating may beproduced on the surface of iron, steel and ferrous articles generally byimmersing such article in a solution of a lead salt of an aliphaticmono-basic hydroxy acid such as glycolic, lactic and gluconic acid, forexample. In a preferred embodiment, a water solution of lead lactatehaving a lead ion concentration of from about 100 to 250 grams per litermay be employed at an operating temperature of from approximately to F.Addition agents of the type commonly added to electroplating baths forthe'purpose of ensuring sound metallic deposits may be utilized in verysmall amounts.

When metallic lead is deposited upon the surface of a ferrous articleimmersed in a water solution of lead lactate at a temperature of 185 F.,for example, a corresponding amount of ferrous lactate is formed. When aconsiderable quantity of ferrous lactate has accumulated and thesolution is then cooled, a very large proportion of the ferrous lactatewill precipitate and may be removed by filtration. It will, of course,carry with it a trace of lead lactate. The precipitate is now dissolvedin hot water and treated with an excess of sulphuric acid to produce aprecipitate of lead sulphate which is filtered out, washed and dried.The filtrate which now comprises the ferrous lactate, lactic acid andsulphuric acid is treated with an excess of an alkaline earth metalhydroxide such as barium or calcium hydroxide, preferably the latter,and the precipitate filtered, Washed and dried. This precipitatecomprises calcium sulphate and ferrous hydroxide, and the filtratecomprises calcium lactate together with the remaining unreacted calciumhydroxide. Now upon the addition of sulphuric acid, a precipitate ofcalcium sulphate is formed completely removing the calcium from thesolution. This precipitate will also be washed and dried. The filtratecomprises a solution of lactic acid together with any remaining excesssulphuric acid. By adding lead oxide (litharge) to such filtrate, thesulphuric acid is removed as lead sulphate which is filtered out, washedand dried, and the filtrate now comprises a solution of lead lactateready to be added to the chemical displacement bath to maintain thelatter at proper concentration for continued deposition of a leadcoating on the ferrous article by chemical displacement.

Based on current market prices, the cost of the necessary indicatedchemicals required in the above steps to reclaim one ton of lactic acidis relatively low and the product thus reclaimed is Worth approximately$500 per ton. The margin is more than ample to cover the cost of laborand facilities required and makes the employment of lead lactate orother lead salt of an aliphatic monobasic hydroxy acid as a source oflead ion for deposition on ferrous articles even more attractive.

The ferrous hydroxide produced may also be heated in the presence of airto form ferric oxide having a substantial value as a pigment andpolishing material. As a charge for steel making furnaces, it has avalue of approximately $50 per ton. In View of the foregoing, it will beseen that it is possible to deposit a pound of lead coating by chemicaldisplacement from a lead lactate solution at a material cost much lessthan would be the case if the lactic acid were not thus cheaplyreclaimed.

In general, it will be seen that we employ lead salts of aliphaticmono-basic hydroxy acids in water solution having a pH of less than 7.The salts other than lead lactate are best employed in comparablepreferred ranges of pH, lead ion concentration, and temperature. Thesalts of lower molecular weights are preferred as being more readilyWater-soluble. The desired solution may be made up by dissolving aWater-soluble lead salt of an inorganic acid, such as lead nitrate, andthen adding the correct amount of the aliphatic mono-basic hydroxy acidbut it is preferred to prepare the solution as described above. The pHmay be adjusted in the usual way by addition of further aliphaticmono-basic hydroxy acid, or of an ammonium or alkali metal hydroxidesuch as sodium hydroxide, as may be required. Some complexes may beformed which tend to remain in solution over a wider pH range.

It is possible to pass a current through the bath to electroplate anadditional coating of lead, if desired, but a great advantage of our newprocess is the fact that an excellent coating for most purposes may beobtained without such additional steps.

The aliphatic mono-basic hydroxy acids ordinarily employed to form thelead salt will of course normally be 8 relatively low molecular weightmono-basic hydroxy fatty acids, more particularly carboxylic acids.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims or the equivalent of suchbe employed.

We therefore particularly point out and distinctly claim as ourinvention:

1. The method of forming a protective substantial, sound, adherent leadcoating on ferrous articles which comprises subjecting such article tothe action of a water solution of a lead salt of an aliphatic mono-basichydroxy acid having a pH below 7 and a lead ion concentration of fromabout 50 to 250 grams per liter at a temperature of from to 200 F. for aperiod of time sufficient to deposit a lead coating of at least 0.0003inch thickness on such article by chemical displacement.

2. The method of forming a substantial, sound, adherent lead coating onferrous articles which comprises subjecting such article to the actionof a Water solution of a lead salt of an aliphatic mono-basic hydroxyacid having a pH below 7 and a lead ion concentration of from about 50to 250 grams per liter at a temperature at least as high as 155 F. for aperiod of time suflicient to deposit a lead coating of appreciablethickness on such article by chemical displacement, such solution alsocontaining a small amount of an organic soundness-enhancing additionagent for inhibiting grain crystallization, of the type commonly addedto electroplating baths.

3. The method of forming a substantial, sound, adherent lead coating onferrous articles which comprises spraying such article with a watersolution of a lead salt of an aliphatic mono-basic hydroxy acid having apH below 7 and a lead ion concentration of from about 50 to 250 gramsper liter at a temperature at least as high as 155 F. for a period oftime sutlicient to deposit a lead coating of appreciable thickness onsuch article by chemical displacement.

4. The method of forming a substantial, sound, adherent lead coating ona ferrous article which comprises spraying such article with a watersolution of lead lactate having a pH of from 2.5 to 5.0, and a lead ionconcentration of from 50 to 300 grams per liter, at a temperature offrom 155 to 200 F., for a period of time sufiicient to deposit suchcoating on such article by chemical displacement.

5. The method of forming a substantial sound adherent protective leadcoating on ferrous articles which comprises subjecting such article tothe action of a Water solution of lead lactate having a pH of from about2.5 to about 5.0 a lead ion concentration of from about 50 to about 300grams per liter, and an operating temperature of from about 155 F. toabout 200 F. for a period of time sufiicient to deposit a continuouscorrosion-resistant lead coating on such article by chemicaldisplacement.

6. The method of forming a substantial sound adherent protective leadcoating on ferrous articles which comprises subjecting such article tothe action of a water solution of lead lactate having a pH of from 3.4to 4.2, a lead ion concentration of from about 100 to about 250 gramsper liter and an operating temperature of from about F. to about F. fora period of time sufficient to deposit a continuous corrosion-resistantlead coating on such article by chemical displacement.

7. The method of forming a substantial sound adherent protective leadcoating on ferrous articles which comprises subjecting such article tothe action of a water solution of lead glycolate having a pH below 7 anda lead ion concentration of from about 50 to 250 grams per liter at atemperature of from 155' F. to 200 F. for a period of time sulficient todeposit a continuous corrosion-resistant lead coating on such article bychemical displacement.

(References on following page) References Cited in the file of thispatent UNITED STATES PATENTS Drantz July 29, 1890 Jordis Nov. 3, 1896Shoemaker Mar. 15, 1921 Alvord Mar. 15, 1938 Sullivan Feb. 4, 1941Mim'ch et al Mar. 25, 1941 10 Booe Mar. 20, 1951 Pessel July 17, 1951Gutzeit Nov. 10, 1953 FOREIGN PATENTS Great Britain July 29, 1917 OTHERREFERENCES Latimer, W. M.: Oxidation Potentials, Prentice-Hall, SigniagoNov. 12, 1946 10 ),p e

1. THE METHOD OF FORMING A PROTECTIVE SUBSTANTIAL, SOUND, ADHERENT LEADCOATING ON FERROUS ARTICLES WHICH COMPRISES SUBJECTING SUCH ARTICLE TOTHE ACTION OF A WATERR SOLUTION OF A LEAD SALT OF AN ALIPHATICMONO-BASIC HYDROXYY ACID HAVING A PH BELOW 7 AND A LEAD IONCONCENTRATION OF FROM ABOUT 50 TO 250 GRAMS PER LITER AT A TEMPERATUREOF FROM 155* TO 200*F. FOR A PERIOD OF TIME SUFFICIENT TO DEPOSIT A LEADCOATING OF AT LEAST 0.0003 INCH THICK-NESS ON SUCH ARTICLE BY CHEMICALDISPLACEMENT.